September 22, 192 1] 



NATURE 



107 



ignorance that such a work was under com- 

 pilation. It leads me to think of past workers in 

 this field of natural history. The foremost among 

 them was the late Dr. William Blanford, the 

 editor and founder of "The Fauna of British 

 India." No one would have known better how 

 much preliminary work there was to do, or what 

 material to obtain; and had he lived he would have 

 prepared the way for it, as he did for vol. i of the 

 MoUusca Series (the Testacellidae and Zonitidaj). 

 It recalls the type of paper he wrote on the 

 animals of Raphaulus, Spiraculum, and other 

 tube-bearing Cyclostomacea so long ago as 1863 

 in "The Annals and Magazine of Natural His- 

 tory." There is even now food for thought in 

 this paper, while it is an indication of how the 

 history of the land operculates should be ap- 

 proached, which is to be looked for in vain in the 

 publication under notice. 



The shells of living species should no longer be 

 treated as if they were fossils, the animal unob- 

 servable, unobtainable ; this I notice under the 

 genera Japonia, Cyclophorus, Alycceus, and 

 Diplommatina, pp. 6, 57, 301, 304, and 349. This 

 neglect of the animal in classification should not 

 thus continue. It is not up to the standard of the 

 present day, and some advance was to be looked 

 for, based on more recent original investigation. 



Space does not admit of quoting many and 

 various errors, but looking at the contents I 

 begin with "The Systematic Index"' and 

 naturally turn to the genera I am best 

 acquainted with. On p. xii I have tc< 

 notice, very fully, an unfortunate, inaccurate 

 record of species under the sub-genus Raptom- 

 phalus of Alycceus; eight species are put into it, 

 whereas it is represented by only one, R. magni- 

 ficus, described by me in "Land and Freshwater 

 Moliusca of India," vol. 2, part 12, p. 366, 

 plate 156, figs. I, la, ib. These figures show 

 that in shell character it is very different and 

 distinct from typical species of Alycceus. As yet 

 it has been found only in the Yamne Valley, a 

 large tributary of the Tsangpo, which comes in 

 on the left bank, not far from the base of the 

 mountains, in the Abor countr}-. 



Mr. Gude has extended the range of this new 

 sub-genus enormously. One of the eight is a 

 species from the Shan-Siam frontier, 500 miles 

 distant, where the sub-genus cannot certainly be 

 expected to extend. All these eight Alycoei are 

 very variable in form, unlike R. magnificus. 

 A glance at the figures will show this. A place 

 for each of them has now to be found in the 

 index, and all on pp. 286, 287, 288, and 289 are 

 out of place. On p. 285 Raptomphalus magnifi- 

 NO. 2708, VOL. 108] 



cus is not the " first species " ; it should be " only 

 species." 



Such a record does not help zoology ; it has gone 

 forth to the world, striking directly at the accuracy 

 of geographical distribution, and before it can be 

 disproved it will be used, trusted, and quoted 

 by workers, both at home and abroad, for years 

 to come. The record in "The MoUusca of India " 

 from the first has been geographical. I have 

 been at pains to show how the distribution of 

 species living in the great valleys of the Hima- 

 layan range changes as we proceed from west to 

 east. This was to be expected, for these great 

 valleys are geologically ancient, isolated one 

 from the other, and separated by great physical 

 features, especially in the Eastern Himalaya by 

 snow-clad meridional ridges. In age these valleys 

 are sufficiently old to be centres of "species de- 

 velopment." We are able to state that there is 

 scarcely a species living in the Ttesta Valley of 

 Sikkim common to the Tsangpo Valley and Abor 

 Hills. The molluscan fauna of the Dafla Hills 

 is remarkable in comparison with both the above 

 areas. Here physical geography comes in to the 

 support of distribution, and shows how accurate 

 the record of the latter should be made. The 

 former tells us that while the Teesta Valley and 

 its neighbours on the west in Nipal, and on the 

 east in Bhutan, have drained for ages into the 

 great depression of the Bay of Bengal, it was 

 comparatively a recent geological change when 

 the Brahmaputra took the same course. Indeed, 

 all evidence goes to show that the Tsangpo origin- 

 ally drained into Burma ; it certainly did so all 

 through the Siwalik period, to go no further back 

 in time. It was the elevation of the Assam range, 

 extending from Eastern Assam to the Garo Hills, 

 which produced this wonderful change in geo- 

 graphy over a vast area. In Eastern Assam the 

 Tertiary sandstones, all derived from the waste of 

 the Himalayas, are elevated to 10,000 ft. and 

 above. This has had everything to say to the dis- 

 tribution of life, particularly the molluscan, both 

 land and freshwater, in this part of India and the 

 eastern frontier, and affected the spread of genera 

 and species. It explains why the molluscan fauna 

 of the Tsangpo Valley is so restricted, and why it 

 cannot be found anywhere, as the distribution at- 

 tributed to Raptomphalus might lead some zoolo- 

 gists to suppose. 



On geological evidence we can presume to say 

 that the Barowli, the Dikrang, and the Ranga of 

 the Eastern Himalaya once flowed directly to the 

 Kyandwen, and the Subansiri and the Tsangpo to 

 the Hkampti Long and head waters of the Irra- 

 wady. It explains the finding of certain species 



